Internal combustion engine propulsion method and corresponding transmission design

ABSTRACT

A case-emphasized propulsion method improves vehicle fuel efficiency. The ratio of the most-used speed to the most-desired speed of an IC engine is employed to control the engine to always run at its optimal working state with an efficient single-stage gear transmission. The propulsion method used with different brands of IC engines demonstrates a reduction in fuel consumption between 5 and 39%. An n-ratio automatic single-stage gear transmission implements the propulsion method. The transmission design executes the proposed propulsion method as well a continuous transmission, but it can also increase the propulsion efficiency about 8 to 18% when applied to replace traditional automatic transmissions or continuously variable transmissions in vehicle drivetrains.

CROSS REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims the benefit of U.S. ProvisionalApplication No. 62/191,220 filed on Jul. 10, 2015. The entire disclosureof the prior application is hereby incorporated by reference herein inits entirety.

BACKGROUND OF THE INVENTION

In order to conserve crude oil and out of concern for the environment,the automotive industry is required to ramp up production of morefuel-efficient vehicles on a tight timeline. As an essential powerconversion system for vehicle propulsion, the technology of the internalcombustion (“IC”) engine is the focus of attention for attempting theimprovement of vehicle efficiency. It is known that the technology ofthe IC engine has its advantages as compared with other energyconversion technologies used on vehicles.

The IC engine is a proven cost-effective technology with a long historyof dominating the markets of power generation, indicating that thetechnology has stood firm with the test of time. Different from otherindirect technologies that convert fuel in the following manner: heatenergy→electrical energy→mechanical energy or chemical energy→electricalenergy→mechanical energy, an IC engine can directly convert the heatenergy of fuel→mechanical energy; thus, t avoids the reduction of fuelefficiency during the process of conversion. The IC engine possessescompetitive ratios of power/weight and power/volume, and can also runwithout pollution if proper fuel is used. Even if fossil fuel is used upin the future, non-fossil fuel replacements cat be easily found. As aresult, the transfer from the fossil fuel era into the non-fossil fuelera will probably occur smoothly with a convenient and inexpensivechange of the power-generating method,

Unfortunately, the efficiency of an IC engine is still low. An IC enginemay only run at around 30% of fuel efficiency. For decades, scientistshave devoted great efforts to improve the efficiency of IC engines indeliberating of many different approaches. Currently,the general ways toimprove the fuel efficiency of IC engine may be understood from Taylor'swork. To have overall understanding of the current IC engine technology,Taylor conducted a systematic review of the IC engine technology. Hesuggested that there could be 6-15% improvement in internal combustionfuel efficiency in the coming decade. Taylor stated that developmentsbeyond the next decade were likely to be dominated by four topics:emission legislation and emission control, new fuels, improvedcombustion; and advanced concepts for energy saving

IC engines could achieve higher efficiency to meet the requirements ofthe raised standards with the development of new technology as listed inthe above four topic. However, upon an investigation of the prior art,it is believed that at least one more topic may also be considered as animportant way to improve the performance of IC engines, that is, thetopic of increasing the fuel efficiency of IC engines. It is known thatthe fuel efficiency of an IC engine is not only related to theefficiency of the engine itself but also related to the efficiency ofthe operating environment. If a high-efficient engine is arranged to runin an improper operating environment, the fuel efficiency in applicationwill remain low.

It is acknowledged that an IC engine could run at its most efficientstate at certain range of engine speeds measured in revolutions perminute (RPM) which produces peak power, and maximizing fuel efficiencyby always allowing the engine to run at the optimum RPM. For decades,scientists have tried to find the best way to use the concept for betterfuel efficiency. The trend of how to use the working properties of an ICengine to achieve optimal fuel efficiency can be understood by thefollowing concise discussions of the prior art.

Osman et al, noted that it was possible to improve the efficiency ofconventional vehicles by intelligent control of the drivetrain. Theytherefore modeled IC engines using neural networks for fuel saving byintelligent control of the transmission. The initial results theypresented showed that considerable fuel savings could be achieved byintelligent selection of optimal shift points.

Maugham et al. considered that, due to low frictional and pumpinglosses, a gasoline engine's fuel efficiency could be maximized at lowspeed, high torque conditions. They indicated that a continuouslyvariable transmission (“CVT”) allowed a drivetrain controller thefreedom to develop a required output power at a range of engine torqueand speed conditions. This flexibility can be used to maximize fuelefficiency. Since controlling a gasoline engine in this range couldcompromise transient vehicle response, the preliminary work had beentaken by them to investigate the potential of charge dilution to controlsteady state engine torque. The outcomes of their research showed thepotential to maintain economy gains with a CVT drivetrain whileimproving a vehicle's drivability.

Sasaki introduced Toyota's new hybrid drivetrain system that included adrivetrain that consisted of a planetary gear mechanism for dividing thedrive force and two motor/generators. Such a system is based on theconcept that uses computer control to optimize engine fuel consumptionand to minimize exhaust emissions.

Ariyono et al. presented their research about the continuously variabletransmissions. They considered that CVT could provide a wider rangetransmission ratio, good fuel economy, smoothly shifting of ratio, andexcellent drivability. They also noted that, with CVT, it was possibleto maintain a constant engine speed based on either its optimum controlline or maximum engine power characteristic. With their work, the use ofAdaptive Neural Network Optimization Control (“ANNOC”) was brought in toindirectly control the engine speed by adjusting pulley CVT ratio.

Hayashi et al. developed a transmission controller for an automobile todeal with the issue of variable loads. Such a development is, actually,an automated manual gear-shift system. Neuro and fuzzy methods areadopted for the controller and the interface between a vehicle operatorand an automobile to make the operator feel comfortable even whenautomobile loads change while traveling.

Scherer et al. introduced the six-speed automatic transmission forpassenger cars developed by ZF Freidrichshafen AG (“ZF”) in 2001. Theymentioned that, with regard to the increasing requirements especially inreduction of CO₂ emissions, a new eight-speed transmission is now underdevelopment in ZF. The main targets for this transmission family are afurther significant reduction in fuel consumption and emissions, gooddriving performance and state-of-the-art driving comfort. The authorsconsidered that the new developments showed that the technology of“conventional” automatic transmissions with torque converter andplanetary gear sets still presented a lot of potential.

Lorenz et al. described that the BMW 750 i had interconnected electronicsystems to control the engine and the automatic transmission. Theyillustrated the concept and interplay of the drivetrain, the drivingstability electronics, and the individual functions, and also describedthe measures taken to make the drive-management system reliable.

Bednarek et al. introduced GM's new six-speed front wheel drive (FWD)family of automatic transmissions. They reported that the newtransmission had a wide overall ratio spread of 6.1:1 which allowed foroptimum adaptation of the drivetrain for various categories of vehicles.The authors considered that the use of the torque converter lockupclutch with electronically controlled slip could lead to the optimum useof the fuel in vehicles.

The following prior art also conducted an investigation about existingtransmission and drivetrain technologies with corresponding analysis offuel efficiency and prediction of the trends of future development.

Hohn described the future trends of automotive drivetrains in Europe. Hepointed out that automotive transmissions for passenger cars in Europehave changed continuously in the last 20 years. The ratio range fortransmissions has increased more and more. He believed that the trend tomore gears for automatic transmissions and manual gear boxes would beon-going. He predicted that, in the future, different concepts would bedeveloped, and semi-automated manual gearboxes, CVTs, and hybrid systemswould be applied even though in the past only manual gearboxes andautomatic transmissions were on the market.

Wu and Sun introduced five major automated transmissions ininternational automobile markets regarding their working principles anddevelopment history as well as the state-of-the-art of the automatedtransmissions. Advantages and disadvantages of automated transmissionswere compared, and development perspective was presented. Forconvenience, representative manufacturers and the application status inthe Chinese market are listed in an accompanying information disclosurestatement.

Wu and Sun also investigated the development history and research statusof the continuously variable transmission. Particularly, they introducedthe basic structure of metal v-belt CVT, and compared the structure andworking principle of the metal belt and chain. With their research, theprinciple and performance of the mechanical-hydraulic control system andelectro-hydraulic control system, especially the slip control strategydeveloped recently were explained, and future CVT development trend werepredicted.

Buscemi discussed that, today, drivers could have more transmissionoptions than before as automatics and manuals are accompanied byautomated manuals (“AMT”), dual clutch transmissions (“DCT”), andcontinuously variable transmissions. The author stated that the mostimportant objective and the main goal for transmission engineers wouldbe to improve fuel efficiency and to perk up overall drivetrainefficiency by reducing drag losses.

Srivastava and Hague studied the significant developments of vehicletransmissions over the last two decades. They considered that a CVTwould offer a continuum of gear ratios between desired limits, whichwould consequently enhance the fuel economy and dynamic performance of avehicle by better matching the engine operating conditions to thevariable driving scenarios. They mentioned that the potential of CVT hadnot been realized in the mass production of vehicle although it couldplay a crucial role to improve vehicle fuel economy, and discussed thechallenges and critical issues for future research on modeling andcontrol of CVTs.

Gilmore emphasized that efficiency goals could represent one of the keyfactors governing drivetrain choice. With specifying three developments,the conventional four-speed manual or automatic transmission wascompeted, and the fuel consumption associated with continuously variableratio and infinitely variable ratio automobile transmissions weresimulated in the situations of urban and highway constant-speedoperation.

Amann reviewed the historical growth in average drivetrain efficiency ofthe US passenger-car fleet, and found that imposition of emissioncontrol caused a temporary retreat, but with the introduction of thecatalytic converter, growth was restored to bring a dramatic decrease inexhaust emissions. He mentioned the dominant position of the gasolineengine and predicted the continuous improvement of transmission.

The prior art shows the essential ways to apply the aforementionedconcept to improve the efficiency of an IC engine, i.e., the vehiclefuel efficiency, with the development of different control schemes andthe introduction of new multiple-speed AMTs, DCTs, and various CVTs.However, through study of the prior arts, it is clear that severalissues remain to be resolved.

It is noted that the prior art was developed with the concept toapproach the optimal fuel efficiency by controlling the IC engine to runin the RPM range around the maximum power since the range is close tothe congregation of the minimum fuel consumption. Such a concept may notalways work because of the following reasons.

The torque decreases with the increase of speed after the maximum torqueis reached. Since the output power is the product of the two, themaximum power may almost stay unchanged in a large range of RPMs. Thismeans that there are many RPMs of maximum power; therefore, it isdifficult to use the above-mentioned concept to approach optimal fuelconsumption.

From the study of the working properties of IC engines, it has beenfound that there are basically two different IC engine working profiles.The first profile is a congregation of the minimum fuel consumption RPMclose to the maximum output torque RPM. The second profile is nocongregation of the minimum fuel consumption RPM near the maximum outputtorque RPM, and the fuel consumption rate simply rises with the increaseof RPM. This means that the concept discussed in the prior art can onlywork with the first profile.

The prior art did not identify the necessary condition to ensure thatthe control method is workable to control a particular IC engine inpractice.

Even though the prior art described that the use of CVTs could increasethe fuel efficiency of an IC engine, they did not specify if CVTs couldhandle power transmission with satisfactory mechanical efficiency.

The prior arts did not present a case-emphasized propulsion controlscheme to satisfy all primary needs for every single vehicle yieldingthe statistic data of the survey that how the vehicle could be used.

There is no claim of a n-ratio auto tic transmission formed by n-pair ofsingle-stage gears that has high mechanical efficiency to convenientlyapproach the case-emphasized propulsion control scheme with ageneralized solution to take advantage of the IC engine's workingcharacteristics yielding the data of survey for all different cases, andat the same time, to provide a comfortable operation similar to theautomatic transmission to make a gear transmission an almost CVT.

It is important to note that, so far, the fuel efficiency of an ICengine equipped on a vehicle coupled with a drivetrain (eithertraditional gearbox/clutch transmission or CVT) is yet to besatisfactory. It is considered that if the above issues can be resolved,it could lead to more efficient fuel consumption. In such a situation,it is necessary to comprehensively understand the IC engine workingproperties to conduct further development.

SUMMARY OF THE INVENTION

According to the present invention, and based on an analysis of workingprofiles of internal combustion engines, a case-emphasized propulsionmethod is generalized to improve vehicle fuel efficiency. With themethod of the present invention, the ratio of the most-used speed to themost-desired speed of an IC engine is employed to control the engine toalways run at its optimal working state with an efficient single-stagegear transmission. Embodiments of the propulsion method of the presentinvention with different brands of IC engines in the marketplacedemonstrate that the present method could reduce engine fuel consumptionbetween 5 and 39%. A design of an n-ratio automatic single-stage geartransmission implements the case-emphasized propulsion method accordingto the present invention. The transmission design of the presentinvention executes the proposed propulsion method as well a continuoustransmission, but it can also increase the propulsion efficiency about 8to 18% if it is applied to replace the traditional automatictransmissions or continuously variable transmissions in vehicledrivetrains.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a variable-speed test of an automotive spark-ignitionengine at wide-open throttle;

FIG. 2 shows a variable-speed test of a compression-ignition engine withdifferent interpretations of a full load;

FIG. 3 shows the specification profile of John Deere's 6068 TF250 ICengine;

FIG. 4 shows the specification data and profile of Deutz's BF4M012 ICengine;

FIG. 5 shows the specification data and profile of Yanmar's 4LHA-150 hpdiesel engine;

FIG. 6 shows the transmission speed and torque from engine shaft to gearpair shaft;

FIG. 7 shows the use of a gear pair to make an engine work at themost-desired speed;

FIG. 8 shows torque changing and fuel reduction ratios with themost-used engine speed range;

FIG. 9 shows a design of an n-ratio automatic single stage geartransmission according to the present invention;

FIG. 10 shows a design of a mating controller according to the presentinvention;

FIGS. 11(a)-16 show alternative designs of a mating controller accordingto the present invention,

DETAILED DESCRIPTION

IC engine tests and the first working profile of an IC engine are nowdescribed.

To ensure that an IC engine can constantly per⁻form in the optimalworking state, it is necessary to know the general relationships of theengine speed versus its fuel consumption and the engine speed versus itsoutput torque. Such relationships can be basically learned throughengine tests. Usually, there are two types of tests: tests at variablespeed, and tests at constant speed. Further, the variable speed testscan be divided into full-load tests and partial-load tests. The constantspeed tests are conducted mainly to determine specific fuel consumption.The following discussions give the basic ideas about the traditionalengine tests.

Variable-speed tests with spark-ignition (Si) engines are now described.

For the maximum power test on the SI engine, the throttle is fullyopened and the lowest speed is maintained by the torque of the brake.When the engine is running in approximation of temperature equilibrium,the fuel consumption is detected. FIG. 1 presents the record data of thevariable-speed test for an automotive Si engine. The profile in FIG. 1is developed with the consideration of atmospheric conditions with thecorrection factor (CF).

Referring to FIG. 1, it can be known that the torque and mean effectivepressure (bmep) are mountain-like curve versus speed; the minimumspecific fuel consumption bsfc) is around the peak location of themountain-like curve of the torque; the friction horsepower (fhp) riseswith the increase of speed, and it rises rapidly because of thereciprocating-piston mechanism; and the indicated horsepower (ihp) isthe sum of the horsepower (bhp) and the friction horsepower, and thehorsepower is the product of the torque and speed.

To conduct a partial-load at variable-speed, for example, 1/N of theload, the brake and throttle are adjusted to achieve 1/N of the maximumpower at each speed. The curve of the brake horsepower versus speedcould be obtained without running the test by merely dividing themaximum power by N. However, fuel consumption will vary accordance withthe changes of the load and throttle.

Variable-speed tests with the compression-ignition (CI) engine are nowdescribed.

It is more difficult to conduct the full-power test of a CI engine atvariable speeds than the SI engine. Through the same procedure of the SIengine test, the brake torque is adjusted until the lowest operatingspeed is reached with the fuel pump injecting a quantity of fuel to makethe exhaust gas slightly colored. This indicates that the engine is nearthe maximum load since some of the fuel is being wasted in smoke. Thisis used to define the full-load at different stages.

In the CI engine, there is no sharp limit and the color of exhaust smokeis a good way to identify the maximum load. The profile of CI enginetests is shown in FIG. 2. The fuel consumption curve in FIG. 2 showsthat the minimum fuel consumption is around the midrange of the enginespeed.

Variable-speed tests of a CI engine at partial loads are done in thesame as a SI engine. It should be emphasized that the fuel consumptioncurve developed with either the full-load or the part-load tests canonly be used for the case which has the same working condition and loadas the tests; otherwise, the profile of tests can only be used as arough reference.

With this kind of profile, the minimum fuel consumption RPM is close tothe maximum output torque RPM which is usually the peak of power RPM.With the display of effective working range of the engine, the depictedprofile of this kind of IC engine will demonstrate that the fuelconsumption simply achieves the minimum value around the maximum torqueRPM.

The constant-speed test is now described.

A constant-speed test is done with a variable throttle from no-load tofull-load to have smoothcurves. Starting with no-load, the throttle isadjusted to get the designated speed. After the first run, the load isadded and the throttle is opened wider to maintain the same speed. Thetest continues until the last run of the full-load is made with thewide-open throttle. In a CI engine test, the last test would have smokein the exhaust gas.

With reference to the aforesaid engine tests and corresponding test dataprofiles, the relationship between the engine speed versus the torqueand the fuel consumption can be generally described as follows: atfirst, with the increase of the speed, the fuel consumption begins todrop and the torque begins to rise; when the engine speed runs into somepositions of the midrange, the fuel consumption drops to the minimumvalue and the torque reaches its peak; and after the engine runs overthis midrange of speed, the fuel consumption will increase and thetorque will decline with the continuous increase of speed.

Through the aforementioned tests, the following two kinds of profilescan be recorded to show the working properties of IC engines.

The first working profile of an IC engine is now described.

The above profiles of FIG. 1 and FIG. 2 demonstrate the generalproperties of IC engine speed versus fuel consumption and torque throughthe tests for the SI type and CI type IC engines respectively. Suchworking properties of an IC engine can be widely seen with thespecifications of IC engines in the marketplaces (refer below to FIG. 3and FIG. 4). For better understanding, such a profile is defined as thefirst working profile of IC engine.

The second working profile of IC engine is now described.

It is noted that there is still another kind of major working profile ofan IC engine. For better understanding, this kind of profile is definedas the second profile of IC engine working properties. FIG. 5 shows thesecond working profile which is obtained with the tests of a Yanmar's4LHA-150hp IC engine.

This kind of depicted profile can be seen with the specifications ofmany brands of IC engines in the market place. With the second profile,the minimum fuel consumption RPM is far away from the maximum outputtorque RPM. Therefore, for effective demonstration of the working range,depicted profile of this kind of IC engine will exhibit that the fuelconsumption increases with the increase of the engine speed. Around themaximum torque, the fuel consumption rate is not close to the minimumvalue. As is mentioned previously, to control the IC engine running atthe peak power RPM for minimum fuel consumption will not work with sucha profile.

The propulsion method developed using the working profiles of IC engineis now described.

Based on the two kinds of working profiles of IC engines, acase-emphasized propulsion method can then be developed to achieveoptimal fuel efficiency. To conduct the development, two terms aredefined here for convenience.

First, it is known that, when an IC engine is applied for the propulsionof a vehicle, it may frequently do its regular work in several differentworking states. The frequently used working states are defined as themost-used working states. The speed and torque related to each of themost-used working states are defined as the most-used speed and themost-used torque.

Second, it is noticed that the most-used working states of an IC enginein a vehicle may be very different trot s most-desired working state.The most-desired working state is the state that the engine conducts theleast fuel consumption. The speed and torque related to the most-desiredworking state are defined as the most-desired speed and the most-desiredtorque correspondingly.

A case-emphasized propulsion method developed by using the first profileis now described.

With the above observation from FIG. 1 to FIG. 4, it is clear that, theoutput torque of an IC engine may achieve the maximum value at certainspeed range that is near the speed of the least fuel consumption. Thistype of profile is identified as the first kind of working profile of anIC engine.

For better understanding of the working properties of an IC engine, thebrake torque curve and bsfc curve in FIG. 1 are adopted here to conductthe following analysis (FIG. 6). FIGS. 1-4 and FIG. 6 indicate how theuse of the unique relationships among engine speed, output torque, andfuel consumption can improve fuel efficiency. FIG. 6 demonstrates thatthe least rate of fuel consumption is around the range from speed d₁ tod₂ with corresponding brake torque from k₁ to k₂. Generally, it is knownthat an IC engine may not necessarily work in such a range. For example,if the engine associated with FIG. 6 is frequently working in the speedrange between e₁ and e₂ with mean torque of k_(e), then acase-emphasized propulsion method can be developed to make full use ofthe working properties of an IC engine.

A basic method of IC engine propulsion for improving fuel efficiency isnow described.

With the case-emphasized propulsion method, in FIG. 6, the range (e₁-e₂)is defined as the most-used speed range. The speed at point e is themean of most-used speed, and it can be approximated by

$\begin{matrix}{{{Speed}\mspace{14mu} e} = \frac{{{Speed}\mspace{14mu} e_{1}} + {{Speed}\mspace{14mu} e_{2}}}{2}} & (1)\end{matrix}$

In FIG. 6, the range (d₁-d₂) is considered as the most-desired speedrange since fuel consumption is the lowest when an engine runs in thisrange. The speed at point d is the mean of the most-desired speed, and

$\begin{matrix}{{{Speed}\mspace{14mu} d} = \frac{{{Speed}\mspace{14mu} d_{1}} + {{Speed}\mspace{14mu} d_{2}}}{2}} & (2)\end{matrix}$

By studying the characteristics of the relationship demonstrated inabove figures, it is known that a high efficient gear transmission canbe used to make the IC engine run in the most-desired speed range, andat the same time, to do the work in its most-used speed range. FIG. 7shows the basic idea of the single-stage gear transmission. FIG. 7illustrates an IC engine 702, an engine shaft 706 turning at speed d,and a transmission shaft 704 turning at speed e.

With this development of single-stage gear transmission, thetransmission ratio is I, and

$\begin{matrix}{I = \frac{e}{d}} & (3)\end{matrix}$

With the transmission ratio, the most-desired speed at the engine shaftcan be transmitted to the most-used speed at the output of transmissionshaft, that is

E=I d

At the same time, the transmitted torque from the engine shaft to thetransmission shaft will be from k_(d1) to k_(d1′), and

k_(1′)=I k_(d1)   (4)

It is clear, if the transmitted torque k_(d1′) at the transmission shaftis larger than or equal to the original torque of the most-used speedk_(e)then, it is possible for the IC engine to run at the most-desiredspeed d with the engine shaft and to do the work at the most-used speede with the transmission shaft. With reference of FIG. 6, theoretically,the rate of fuel consumption will drop from j_(e) to j_(d).

With the above analysis of the design method, it appears that the ICengine can run in the most-desired speed with the lowest fuelconsumption to do the work that originally should be done at themost-used speed. However, to ensure the proper application of themethod, it is necessary to conduct the following analysis for thefeasibility study.

Discussions of the feasibility of the propulsion method of the presentinvention including the necessary condition to implement the propulsionmethod are now described.

Since the propulsion of an IC engine is not only related to the enginespeed but also to the engine output torque, to use the method, thetransmitted output torque must be larger than or equal to the most-usedtorque as above-discussed, that is

k_(d1′)≦k_(e)

or, I k_(d1)≦k_(e)   (5)

In practice, the condition (5) must be checked to ensure the applicationof the method, and the restriction is considered the necessary conditionof the proposed propulsion method.

With study of the engine output torque and output speed, it appears thatthe mountain-like working curve of an IC engine make the propulsionmethod available. It provides the possibility to have a propertransmission ratio to develop a pair of output speed and torque to matchthe most-used speed and torque.

It is noted that, if the most-desired speed range is far away from themost-used speed, the transmission ratio could be relatively large. Insuch a situation, the output torque at the transmission output shaft maynot match the most-used torque; thus, the proposed design method cannotbe applied properly. However, in this case, by using a proper speed thatis closer to the most-used speed as a replacement of the most-desiredspeed, it will make the transmission ratio smaller. In this way,although fuel consumption is slightly higher than the ideal situation,it will still take advantage of the working properties of an IC engineto achieve better fuel efficiency.

The high mechanical efficiency of gear transmission makes thedevelopment possible.

A gear pair is used to implement the above method; thus, it is necessaryto check if the efficiency gain is significantly larger than theefficiency loss with the gear transmission. The following discussionswill present the energy loss with the se of the gear pair.

The major energy loss with the propulsion method is caused by the use ofthe single-stage gear pair. To conduct the efficiency analysis of a gearpair, the following method may be used for basic understanding:

$\begin{matrix}{{E({efficiency})} = {( {100 - P} )\%}} & (6) \\{P = \frac{50\; {\mu ( {{Hs}^{2} + {Ht}^{2}} )}}{\cos \; {\alpha ( {{Hs} + {Ht}} )}}} & (7) \\{{Hs} = {( {R_{g} + 1} )\{ {\sqrt{\lbrack {( \frac{R_{0}}{R_{P}} )^{2} - {\cos^{2}\alpha}} \rbrack} - {\sin \; \alpha}} \}}} & (8) \\{{Ht} = {\frac{R_{g} + 1}{R_{g}}\{ {\sqrt{\lbrack {( \frac{r_{0}}{r_{P}} )^{2} - {\cos^{2}\alpha}} \rbrack} - {\sin \; \alpha}} \}}} & (9)\end{matrix}$

Here, R_(g) is the gear ratio, R_(o) is the outside radius of gear (m),r_(o) is the outside radius of pinion (m), R_(p) is the pitch radius ofthe gear (m), r_(p) is the pitch radius of the pinion(m), E is theefficiency of the gear pair (%), P is the power loss of the gear pair asa percentage of the input power (%), α is the pressure angle,and μ isthe coefficient of friction.

If a pair of spur gears is used, and the gear parameters are: α⁼20⁰,R_(g)=1.2, module=2, pinion teeth=25, gear teeth=30, and the gear is thefull depth tooth type, it leads to R_(o)=26 mm, r_(o)=22 mm, R_(p)=24mm, and r_(p)=20 mm. With the above formulas (9) to (12), the gear pairefficiency is higher than 99%. Further, since the friction coefficientfor ball bearings is about 0.001˜0.008, the efficiency of the one-stagegear pair is G_(η), and G_(η)>98%. Therefore, using one-stage spur gearpair is considered acceptable to implement the design method with thisresearch. The same conclusion can also be obtained from differentcredited resources listed in an accompanying information disclosurestatement.

Examples of efficiency gain with the propulsion method of the presentinvention are now described.

To verify the gain of efficiency with the propulsion method, severaldifferent IC engines made by different manufacturers in the market placewill be used as examples to analyze if such a propulsion method reallyworks.

Example 1 is an application using John Deere's 6068TF250 IC engine.

If a John Deere's 6068TF250 IC engine is used to implement thepropulsion method, its profile in FIG. 3 can be used. With the referenceof FIG. 3, if a specific case of most-used working state is designatedwith the most-used speed of 2300 RPM and most-used torque of 624 Nm, thecorresponding fuel consumption is about 232 gram/kw per hour. With thiskind of IC engine, the most-desired working state holds the speed of1800 RPM and the torque of 746 Nm. At the most-desired working state,the fuel consumption is about 215 gram/kw per hour. With the proposedpropulsion method, the transmission is

$I = {\frac{e}{d} = \frac{23}{18}}$

When the engine shaft is at 1800 RPM with the output torque of 746 Nm,the gear pair shaft will be 2300 RPM with corresponding output torqueabout

$T_{2300\mspace{14mu} {RPM}} = {{746\frac{1}{I}} = {584\mspace{14mu} {Nm}}}$

In this case, the torque changing ratio of reduction, T_(I) will beabout

$T_{I} = {\frac{624 - 584}{624} = {6\%}}$

If 5% of reduction of the output torque is considered acceptable, thenthe propulsion method may not be very suitable for this specific case touse John Deere's 6068TF250 IC engines since the output torque is muchless than the torque required.

In this case, if 6% reduction of the output torque is still workablewith the proposed method, the fuel consumption will decline about

$\eta_{I} = {\frac{232 - 215}{232} = {7.3\%}}$

By subtracting the mechanical consumption of the added gear transmission(about 1˜2%,) it can still hold the gain of fuel reduction around 5%. Itshows that the improvement of fuel efficiency is significant.

Example 2 is an application using DEUTZ's BF4M2012 IC engine.

When the DEUTZ's BF4M2012 IC engine is employed to process thepropulsion method, its working properties shown in FIG. 4 can be appliedfor the initial analysis. Referring to FIG. 4, it shows that the speedand torque associated with the most-desired working state are around1350 RPM and 380 Nm. It also indicates that the fuel consumption ratecorresponding to the most-desired working state is about 210(gram/kw-hr). If this kind engine is designed to frequently do the workat the working state of output speed 2400 RPM and output torque of 300Nm, then, the designated working state can be considered as themost-used working state, that is, the most-used speed is 2400 RPM andthe most-used torque is 300 Nm. To employ the propulsion method, thetransmission ratio is

$I = \frac{24}{13.5}$

In this case, the transmitted torque from the engine shaft to the gearshaft is about 213 Nm, The torque changing ratio is about 28%. Itsuggests that the proposed propulsion method may not be adopted withthis specific working state since the necessary condition is notsatisfied, that is, the working torque is too small to handle theoriginal torque requirement for vehicle propulsion.

A case-emphasized propulsion method developed using the second profileis now described.

Since the second profile of IC engine working properties is differentfrom the first profile, the above-mentioned propulsion method cannot beused for an IC engine with the second profile. To know how the methodcan be applied with an IC engine possessing the second profile, thefollowing example provides a detailed demonstration.

Example 3 is an application using YANMAR's 4LHA-150hp IC engine.

By observation of FIG. 5, it is known that Yanmar's 4LHA-150hp IC engineis a typical case of the second profile. To apply the propulsion methodwith such an engine, the most-desired speed should be chosen as slow aspossible yielding the constraint of the output torque.

When a Yanmar's 4LHA-150hp IC engine is equipped to thrust a fullyloaded boat, it often runs with the working state of output speed andoutput torque around 3200 RPM and 320 Nm respectively.

In such a case, the working state is considered as the most-used speedand the most-used torque. Referring to FIG. 5, the most-desired speedcan he chosen around 2650 RPM since at this speed the output torqueachieves the maximum value. If the most-desired working state is chosenwith speed of 2650 RPM and output torque of 380 Nm, the correspondingfuel consumption is about 1,706×10⁵ cm³/hour. From FIG. 5, it can alsodetermine the fuel consumption corresponding to the most-used workingstate, which is about 2.843×10⁵ cm³/hour. Therefore,to implement theproposed design method in this case, the transmission ratio with thisdesign method will be

$I = {\frac{3200}{2650} = \frac{64}{53}}$

This means that when the engine shaft is at the speed of 2650 RPM, thegear shaft will be 3200 RPM with an output torque T_(3200 RPM), and

$T_{3200\mspace{14mu} {RPM}} = {{380\; \frac{1}{I}} = {315\mspace{14mu} {Nm}}}$

The output torque changing ratio of reduction is about

$T_{I} = {\frac{320 - 315}{320} = {1.6\%}}$

which should be tolerable. In this case, with the application of thismethod, the consumed fuel will reduce about 1.137×10⁵ cm³/hour. Thismeans that the fuel consumption will decrease about

$\eta_{I} = {\frac{{2.843 \times 10^{5}} - {1.706 \times 10^{5}}}{2.843 \times 10^{5}} = {40{\%.}}}$

Considering the energy loss of the gear transmission, the reduction offuel consumption is around 39%. Such an outcome is absolutelyremarkable. Certainly, such a result is based on the assumption of themost-used working state; however, the example does show the possibilityof great fuel saving with the proposed IC engine propulsion method.

In application, the working state of an engine is very different anduncertain. For better understanding, the following example will showthat different working state conduct different energy saving. In thiscase, if the most-used working state is assumed to have the most-usedspeed of 2800 RPM and the most-used torque of 370 Nm, the correspondingfuel consumption is about 2.009×10⁵ cm³/hour. Therefore, thetransmission ratio for this case to use the method will be

$I = {\frac{2800}{1650} = \frac{56}{53}}$

Here, if the most-desired working state is the same as the last case,with this transmission ratio, transmission shaft will run at a speed of2800 RPM with the output torque about

$T_{2800\mspace{14mu} {RPM}} = {{380\; \frac{1}{I}} = {360\mspace{14mu} {Nm}}}$

The torque changing ratio of reduction will be around

$T_{I} = {\frac{370 - 360}{370} = {2.7\%}}$

which is less than 5%. In this case, if the reduction of the torque isconsidered acceptable, the fuel consumption will reduce about

$\eta_{I} = {\frac{{2.009 \times 10^{5}} - {1.70 \times 10^{5}}}{2.009 \times 10^{5}} = {15{\%.}}}$

Taking the energy loss of the gear transmission into consideration, theefficiency will still increase about 14% against the original fuelconsumption. The result demonstrates that the improvement of fuelefficiency is also very significant.

The above analysis demonstrates that, if the conditions are optimum, theproposed propulsion method could decrease the fuel consumption up to5˜39% as comparison with the traditional way of propulsion. To differenttypes of IC engines, the working profiles are very different. FIG. 8below provides the basic information about the fuel reduction ratio andthe torque changing ratio for the type of YANMAR's 4LHA-150hp DieselEngine corresponding to the most-used speed range from 2650˜3200 RPM. Ifthe most-used working state of a YANMAR's 4LHA-150hp Diesel Engine isknown, one can check the data of FIG. 8 to know if such a working statecan make good use of the propulsion method with such a type of DieselEngine. It is noted that, to each individual engine of this type, theprofile of the fuel reduction ratio and the torque changing ratiocorresponding to the most-used speed range may slightly different fromFIG. 8 since this profile is developed from the mean value of tests ofsuch a type. However, the statistical result is able to scientificallyverify the proposed propulsion method and to ensure its application tosave energy.

Design procedures of the generalized case-emphasized propulsion methodare now described.

It is known that, in many applications, an IC engine is generallyoperated to run in various cases of the most-used working states. Toresolve such a problem, a multiple ratio single-stage gear transmissionshould be used to implement the proposed case-emphasized propulsioncontrol scheme. The following discussions provide the basic idea andprocedure to determine the ratios of the single-stage gear transmission.

All of the most-used speeds and corresponding most-desired speeds areidentified. If there are several different most-used working states foran IC engine powered vehicle, it is necessary to define thesecorresponding most-used speeds and most-used torques and to identify themost-desired working state one by one. For example, the IC engine of afour-seat passenger car may frequently run with one or more of thefollowing four cases:

-   Case 1: The car is frequently driven on downtown resident streets    under mean torque of k_(e1) corresponding to a load of 2 persons at    the mean speed e₁ which is equal to speed limit of 25 km/hour. (The    corresponding most-desired speed in tests is d₁ and the    corresponding most-desired torque is k_(d1).)-   Case 2: The car is frequently driven on downtown street under mean    torque of k_(e2) corresponding to a load of 2 persons at the mean    speed e₂ which is equal to speed limit of 45 km/hour. (The    corresponding most-desired speed in tests is d₂ and the    corresponding most-desired torque is k_(d2).)-   Case 3: The car is frequently driven on country roads under mean    torque of k_(e3) corresponding to a load of 2 persons at the mean    speed e₃ which is equal to speed limit of 80 km/hour. (The    corresponding most-desired speed in tests is d₃ and the    corresponding most-desired torque is k_(d3).)-   Case 4: The car is frequently driven on a freeway under mean torque    of k_(e4) that is corresponding to a load of 2 persons at the mean    speed e₄ which is equal to speed limit of 110 km/hour. (The    corresponding most-desired speed in tests is d₄ and the    corresponding most-desired torque is k_(d4).)    With this example, a 4-ratio single-stage gear transmission can be    used to implement the case-emphasized propulsion method.

Next, the transmission ratios must be determined. Based on the abovetesting results, determine the transmission ratios corresponding to theabove four cases, i.e.,

${I_{1} = \frac{e_{1}}{d_{1\;}}},{I_{2} = \frac{e_{2}}{d_{2}}},{I_{3} = \frac{e_{3}}{d_{3}}},{{{and}\mspace{14mu} I_{4}} = \frac{e_{4}}{d_{4}}}$

to transmit the most-desired speed to the corresponding most-used speed

Next, the necessary working condition must be checked. The necessaryworking condition that the propulsion method could be realized is thatthe output power of the IC engine at the most-desired working state isequal to or larger than the needed power corresponding to the most-usedworking state. Therefore, the following conditions must be true

k_(d1′)≧k_(e1), k_(d2′)≧k_(e2), k_(d3′)≧k_(e3), and k_(d4′)≧k_(e4)

Once all the above conditions are true, this leads to the design of asingle-stage gear transmission with corresponding transmission ratiosI₁, I₂, I₃, and I₄. A corresponding transmission can always let theengine work around the most-desired working states, and guarantee theminimum fuel consumption.

A design of an N-ratio automatic transmission is now described.

For each different IC engine powered vehicle in a given application, themost-used working states and the most-desired working states could bevery different. It is a challenge to develop a one-stage geartransmission of multiple ratios with high efficiency to execute theproposed propulsion method of the present invention as it must becompact in volume and light in weight as well as convenient inoperation. Since the transmission ratios are uncertain for each of thecustomers based on the case-emphasized propulsion method, it isdifficult to have a transmission with multiple ratios to meet the needsof all IC engine control of a vehicle in general. More critically, theuncertain transmission ratios cannot use mass production to achieve thecost-effectiveness of engineering.

To cover all kinds of different transmission ratios for differentvehicles to achieve optimal fuel efficiency, one generalized solution isto use a continuous variable transmission (CVT). A CVT is able toprovide a continuous transmission ratio to meet all kinds of differentcases. It is noted that, if the mechanical efficiency was satisfied, aCVT would be the best choice to easily provide suitable transmissionratios to execute the case-emphasized propulsion method. Even thoughCVTs have been widely used in vehicles, the issue here is: “Can a CVT inthe existing inventory be qualified to do so?”

Upon review of the above discussed prior arts, a serious concern israised about using CVT to improve the fuel efficiency of a vehicle. Bymaking full use of the IC engine's working characteristics, a CVT cancontrol the IC engine and easily provide suitable transmission ratios toimprove the IC engine output fuel efficiency. The problem is that, themechanical efficiency of a CVT in the existing inventory does not appearqualified, and a CVT may actually drag down the overall fuel efficiency.

The hydraulic CVT technology is able to provide continuous transmissionratio and it has been widely equipped on vehicles. Disappointedly, themechanical efficiency of CVT applied in vehicles is very low, which isusually around 80%. In recent years, the efficiency of hydraulic CVTused in vehicles has been improved, and the efficiency has been claimedup to 90˜95% with the report published in New York Times entitled:“Hydraulic Transmission for Fuel Savings” by J. Faludi on Feb. 11, 2005.Unfortunately, there is no corresponding technical verification withthis report as a reliable reference. Therefore, the efficiency ofhydraulic transmission still can only be considered about 80%.

With the existing inventory of mechanical types of CVTs that are widelyused in automotive transmission design today, in general, since thesetypes of CVTs are all based on using frictional force to transmit power,the frictional consumption of energy is unavoidable. As a result, theefficiency of such types of CVT could never be satisfactory. With recentreport in industry, the efficiency of an advanced mechanical CVT isaround 80-90%. Further, the other creditable reference also considersthe mechanical efficiency of mechanical CVT to be around 80%.

It is clear that if the current CVT technology were used to execute thecase-emphasized propulsion method, it would worsen the overall fuelefficiency of an IC engine rather than improve it. Given this situation,a generalized solution to develop an n-ratio automatic transmission isproposed. Here, the “generalized” solution means that the developmentgives not only a generalized solution for the control of all the ICengines with two different profiles, but also provides a generalizedsolution of an almost CVT profile to approximate the required ratiosyielding the case-emphasized survey for all different IC engine poweredvehicles.

The design criteria of the n-ratio automatic transmission is nowdescribed.

The design criteria of a n-ratio automatic transmission to improve ICengine propulsion fuel efficiency according to the present invention areachieving not only the optimal IC engine fuel efficiency but also highoverall power, transmitting efficiency of the drivetrain of the vehicle,providing the function of an almost continuous variable transmission,conducting cost-effective design and manufacturing with mass productionthat is suitable for all different cases, emulating an automatictransmission with the elimination of clutch that is convenient tooperate, achieving high mechanical efficiency of transmission, andsetting up specific control modes with the almost continuous variabletransmission to cover all the possible cases of the most-used workingstates.

It is noted that if an IC engine with an nominal power output of P_(out)is coupled with the traditional CVT transmission which possesses amechanical efficiency of η_(m), the output power after the transmissionis P_(w), and

P_(w)=P_(out) η_(m)

If the same IC engine is applied with the proposed propulsion method,the power output will be P_(nout), and

P_(nout)=P_(out)(1+η_(i))

Here, η_(i) is the increase of fuel efficiency, and it is around 5-39%as above-mentioned if the condition of applying the propulsion method isfit. When the engine equips an n-ratio automatic transmission that has amechanical efficiency η_(n), the output power after the transmission is

P_(nw)=P_(nout) η_(n)

With comparison of the two, the ratio of additional reduction of fuelconsumption with the n-ratio automatic transmission is

${{Ratio}\mspace{14mu} {of}\mspace{14mu} {additional}\mspace{14mu} {reduction}} = {\frac{P_{nw} - P_{w}}{P_{w}} = \frac{{( {1 + \eta_{i}} )\eta_{n}} - \eta_{m}}{\eta_{m}}}$

Through the earlier discussions, it is known that η_(m) is about 80˜90%and η_(n) is around 98%. Therefore, the maximum and the minimum ratios(refer to R_(max) and R_(min) respectfully) of fuel reduction can becalculated as follows [21, 22, 23] can be obtained as follows:

$R_{{ma}\; x} = {\frac{{( {1 + {39\%}} )98\%} - {80\%}}{80\%} = {70.2\%}}$and$R_{m\; i\; n} = {\frac{{( {1 + {5\%}} )98\%} - {90\%}}{90\%} = {14.3\%}}$

The results demonstrate that, if an IC engine is applied with theproposed propulsion method and coupled with an n-ratio automatictransmission, it could reduce overall fuel consumption ∈[14.3%, 70.2%]in comparing to the traditional propulsion method and traditional CVT.

The conceptual design of a n-ratio automatic transmission is nowdescribed.

Based on above-discussed design philosophy and expectations, a possibleconceptual design of a n-ratio automatic transmission is developed(refer to FIG. 9) to implement the propulsion method.

With this design shown in FIG. 9, there are n numbers of gear pairs 902that are mounted on the two shafts (transmission output shaft 904 anddriving shaft 906, which is in turn coupled to the engine output shaft912) of the single-stage gear transmission, which have correspondingtransmission ratios of I₁, I₂, . . . , I_(n-1), I_(n). Each gear pair issupported by bearings on the shaft to ensure that at least one gear ofthe pair can rotate around the shaft without restriction. Originally,all the gear pairs of n-ratio are mounted together with the fake matingstate. This means that, at first, all the gear pairs mounted on thetransmission shaft can rotate around the shaft with no restrictionyielding the support of the rotational bearings. In application, theproper transmission ratio I close to the ratio of the most-used speed tothe most desirable speed with an arbitrary case of propulsion can bematched by the transmission controller 908. If the ratio interval of then-ratio automatic transmission is relatively narrow, the effect will berelatively good.

All the mounted gear pairs 902 are under control by the matingcontroller 908 associated with each of the gear pairs 902. In theworking process, only one gear pair can be engaged by the correspondingcontroller at a time to deliver the relevant transmission ratio, and theother gear pairs are all kept in the fake mating state, which will notconsume energy since the acting force on each of the gear pair in fakemating state is negligible. FIG. 10 shows a possible conceptual designof the controller 910 previous shown in FIG. 9, and demonstrates theworking principle of how it can control the gear pair to execute thepropulsion method.

In FIG. 10, it shows the basic design of the mating controller. It showsthat, if the gear pair is controlled to provide the correspondingtransmission ratio, the electromagnetic actuator 1002 will be actuated.With the expansion of the actuator, the contacting force between theclutch blades 1004 will fix the gear on the shaft to rotate. In thisway, this mating gear pair can begin to transmit power and motion.Obviously, at the same time, the other gear pairs that have not beenlocked will also rotate with bearings freely on the shaft. In this way,the support bearings 1006, 1008 experiences very small contact loads,and the resultant energy consumption can be ignored. Such a type ofelectromagnetic clutch has been widely used in CNC machine systemcontrol with excellent working performance.

Although the simple frictional clutch technology can provide aneffective engagement to fix the gear on the shaft, one may argue thatthe application may cause extra energy loss because it has to provideconstant pressure to have the friction force to fix the gear with theshaft and there may be always the relative displacement between the twosets of clutch blades 1004 to cause a waste of energy and to increase offrictional heat.

To resolve such issues, an extra locker can be developed with the matingcontroller. In FIG. 10 shows that, after the engagement of thefrictional blades 1004, once the relative speed between the two rotatingparts is slowed enough, the pins of a locker 1010, 1012 will be actuatedin the slot to fix the two together and then all actuators can bereleased without the need to maintain the pressure. The pins will becontrolled by a trigger system. If the gear pair i is in need ofdisengagement, the trigger system will be pushed down by a smallactuator to set the gear pair i in a fake mating state. Thus, the abovearguments can be fairly resolved.

It is noted that t are numbers of conventional technologies of clutchesand lockers that can be conveniently adopted for the conceptual design.In order to realize the conceptual design, all different technologies ofclutches and lockers should be compared against each other to locate theone capable of carrying out the above function effectively at low cost.

Alternative mating controllers suitable for use in the n-ratio automaticsingle-stage gear transmission shown in FIG. 9 are shown in FIG. 11(a),FIG. 11(b), FIG. 12(a), FIG. 12(b), FIG. 13, FIG. 14, FIG. 15, and FIG.16.

Referring now to FIG. 11(a) a first alternative mating controller isshown in the separated state. The mating controller includes a drivenmember 1102, a driver 1104, an actuator 1106, an engaging ball 1108, anda shaft 1110. The actuator 1106 is in a first state such that theengaging ball 1108 does not make contact with the driven member 1102.Referring now to FIG. 11(b) the first alternative mating controller isshown in a fixed state, where the same elements are shown with the samereference numerals. The actuator 1106 is in a second state such that theengaging ball 1108 is forced to make contact with the driven member1102. The electrical energy for the actuators can be provided throughthe shaft 1110 as is known in the art.

Referring now to FIG. 12(a) a second alternative mating controller isshown in the separated state. The mating controller includes a drivenmember 1202, a driver 1204, an actuator 1206 having a rounded tip, anengaging ball 1208, and a shaft 1210. The actuator 1206 is in a firststate such that the engaging ball 1208 does not make contact with thedriven member 1202. Referring now to FIG. 12(b) the first alternativemating controller is shown in a fixed state, where the same elements arcshown with the same reference numerals. The actuator 1206 is in a secondstate such that the engaging ball 1208 is forced to make contact withthe driven ember 1202. The electrical energy for the actuators can beprovided through the shaft 1210 as is known in the art.

Referring now to FIG. 13, a close-up and partial view of the firstalternative mating controller is shown in the separated state whereinthe driven member 1302, the driver 1304, the actuator 1306, and theengaging ball 1308 are shown. Referring now to FIG. 14, a close-up andpartial view of the first alternative mating controller is shown in thefixed state wherein the driven member 1402, the driver 1404, theactuator 1406, and the engaging ball 1408 are shown.

Referring now to FIG. 15, a close-up and partial view of the secondalternative mating controller is shown in the separated state whereinthe driven member 1502, the driver 1504, the actuator 1506, and theengaging ball 1508 are shown. Referring now to FIG. 16, a close-up andpartial view of the second alternative mating controller is shown in thefixed state wherein the driven member 1502, the driver 1504, theactuator 1506, and the engaging ball 1508 are shown.

With the propulsion method and the corresponding n-rate transmissionaccording to the present invention, the price of a vehicle will behigher than a conventional one because of the additional work andmanufacturing cost. However, the following analysis indicates thebenefits are worth the extra costs to carry out the propulsion method:no clutch is needed with the n-ratio automatic transmission, which canreduce the cost considerably, and the method and transmission accordingto the present invention could increase fuel efficiency ∈[14.3%, 70.2%]by comparing with the traditional technology.

By considering that the mean of 42.25% fuel reduction can beaccomplished, if the average travelling distance of a passenger carwhich has a low mileage of 10.5 km/Lite (25 mpg) is about 16000 km peryear, then, it will save 644 litters (170 gallons) in one year. As thecurrent price for one liter of gasoline is about $0.79˜$1.06 ($3˜$4 pergallon,) it will save an average of $49.61 per month. With reference ofthe MACRS-GDS (Modified Accelerated Cost Recovery System-GeneralDepreciation System) Property Class of the US, the clarified life of acar is 5 years. In a relatively gloomy financial situation with a lowannual interest rate of 2.5% compounded monthly, the gain from thesaving of gasoline will be calculated with the uniform series compoundamount as follows [24]:

${{The}\mspace{14mu} {gain}} = {{A\frac{\; {( {1 + i} )^{n} - 1}}{i}} = {{{\$ 49}{.61}\; \frac{( {1 + {0.208\%}} )^{60} - 1}{0.208\%}} = {{\$ 3167}{.22}}}}$

Here, A is the monthly saving payment, i is the effective monthlycompound interest rate of the loan, and n is the total time periods ofclarified life of a car. The above benefits should well compensate theextra cost of the manufacturing of the transmission.

Additional considerations with the design are described,

By using a series of constant-open switches to control the n-ratiotransmission in a row, the n-ratio transmission will increase ordecrease the speed ratio gradually to have the effect of an almost CVT.Such an effect will make the operation of the vehicle convenientespecially for these drivers who do not like to drive with the use ofthe manual transmission.

Furthermore, because the n-ratio automatic transmission is almost like atraditional CVT, it can be controlled as the traditional CVT to dealwith the special case of hill-climbing with transmission near or just atthe desired ratio.

As for vehicle reversing control, since it is an extreme case inapplication, and the time period is short, no special considerationabout fuel efficiency is necessary. The traditional gear transmissionfor reversing process can be used here with the conceptual design. FIG.9 shows the reverse (R) output of the transmission. All the controlsassociated with different cases of a vehicle can be designed in the waysimilar to the traditional CVT in an automatic/semi-automatic manner bymeans of embodiment of electro-mechanical systems.

To improve the efficiency of IC engine for vehicle propulsion, ageneralized propulsion method has been provided. With this development,it can not only reduce the fuel consumption but also deliver a n-ratiotransmission possessing high mechanical efficiency.

Through the theoretical verification of the propulsion method by usingdiffer models of IC engine in the market place, the overall result showsthat the fuel consumption of the engine could reduce about 5˜39%. Theconceptual design of the n-ratio automatic transmission with thisresearch provides an effective way to execute the proposed propulsionmethod, which also provides an effective means to improve overallpropulsion fuel efficiency. Significantly, in comparison with current ICengine propulsion coupled with traditional CVT, it could achieve thefuel reduction ∈[14.3%, 70.2%].

With this development, the cost of the new type of proposed transmissionmay be higher than before; however, the savings on gasoline can wellcompensate the manufacturing cost. In fact, the above-discussed savingis very conservative since the actual useful life of a car is muchlonger than the classified depreciation life. Therefore, the gain fromsavings on gasoline will actually be much higher, and consequently,should greatly compensate the higher price for the vehicle owner.

Furthermore, the significance of the method and transmission of thepresent invention is not just for saving money, and the followingoutcomes should be especially emphasized:

It is known that, in the United States alone, there are about 100million cars running on the highway every year and the average mileagefor a car is about 16000 kilometers. With this case-emphasizedpropulsion method, it could save about 64400 million litters (about17014.5 million gallons) of gasoline each year. The result is definitelynoteworthy.

To the automotive industry, obviously, such outcomes are helpful toachieve the goal of the stricter emissions limits for vehicles, and toattain the overall or industry average fuel efficiency standard. Withexpectation, the realization of this research should generate a greatimpact to the environment and the economy of our world.

The invention has been described in detail with reference to preferredembodiments thereof. However, it will be appreciated by those skilled inthe art that changes may be made in these embodiments without departingfrom the principles and spirit of the invention, the scope of which isdefined in the appended claims and their equivalents.

We claim:
 1. An n-ratio automatic single-stage gear transmissioncomprising: a driving shaft; a transmission output shaft; and aplurality of gear pairs, wherein a first gear in the gear pair isselectively coupled to the driving shaft using a first matingcontroller, wherein a second gear in the gear pair is selectivelycoupled to the transmission output shaft using a second matingcontroller, wherein the gear pairs each have a distinct gear ratio, andwherein the first and second mating controllers comprise an engagingball for effectuating a separated state and a fixed state.
 2. Thetransmission of claim 1, further comprising a transmission controllerfor controlling the mating controllers.
 3. The transmission of claim 1,wherein only one gear pair is coupled to the driving shaft and thetransmission output shaft at a time.
 4. The transmission of claim 1,wherein each gear ratio corresponds to a most-used working state for anIC engine.
 5. The transmission of claim 4, wherein the most-used workingstate comprises a downtown resident street working state.
 6. Thetransmission of claim 5, wherein the downtown resident street workingstate comprises a speed limit of 25 km/hour.
 7. The transmission ofclaim 5, wherein the downtown resident street working state comprises aspeed limit of 45 km/hour.
 8. The transmission of claim 4, wherein themost-used working state comprises a country roads working state.
 9. Thetransmission of claim 4, wherein the most-used working state comprises afreeway working state.
 10. The transmission of claim 1 comprising atleast five gear pairs.
 11. The transmission of claim 1, wherein thefirst mating controller comprises a driven member coupled to the firstgear, a driver coupled to the driving shaft, and an actuator forselectively positioning the engaging ball n the separated state and inthe fixed state.
 12. The transmission of claim 11, wherein the actuatorcomprises a flat upper surface for interacting with the engaging ball.13. The transmission of claim 11, wherein the actuator comprises arounded upper surface for interacting with the engaging ball.
 14. Thetransmission of claim 11, wherein power is supplied to actuator throughthe driving shaft.
 15. The transmission of claim 1, wherein the secondmating controller comprises a driven member coupled to the second gear,a driver coupled to the transmission output shaft, and an actuator forselectively positioning the engaging ball in the separated state and inthe fixed state.
 16. The transmission of claim 15, wherein the actuatorcomprises a flat upper surface for interacting with the engaging ball.17. The transmission of claim 15, wherein the actuator comprises arounded upper surface for interacting with the engaging ball.
 18. Thetransmission of claim 15, wherein power is supplied to the actuatorthrough the transmission output shaft.
 19. The transmission of claim 1further comprising a reverse gear pair, wherein first and second gearsof the gear pair are coupled together with a reverse gear.
 20. A methodof improving the efficiency of an IC engine, the method comprising:providing a driving shaft coupled to an engine output shaft of an ICengine; providing a transmission output shaft; and providing a pluralityof gear pairs, wherein a first gear in the gear pair is selectivelycoupled to the driving shaft using a first mating controller, wherein asecond gear in the gear pair is selectively coupled to the transmissionoutput shaft using a second mating controller, wherein the gear pairseach have a distinct gear ratio, and wherein the first and second matingcontrollers comprise an engaging ball for effectuating a separated stateand a fixed state.